From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from ch1outboundpool.messaging.microsoft.com (ch1ehsobe002.messaging.microsoft.com [216.32.181.182]) (using TLSv1 with cipher AES128-SHA (128/128 bits)) (Client CN "mail.global.frontbridge.com", Issuer "MSIT Machine Auth CA 2" (not verified)) by ozlabs.org (Postfix) with ESMTPS id C8F0E2C0354 for ; Tue, 29 Oct 2013 23:53:46 +1100 (EST) From: Chen Guangyu-B42378 To: Timur Tabi Subject: Re: [PATCH 2/3] ASoC: fsl_ssi: Add dual fifo mode support Date: Tue, 29 Oct 2013 12:53:35 +0000 Message-ID: References: <02f8867363ed3038a0a70703856e4b642fef4339.1383047327.git.b42378@freescale.com>, <526FAD41.2000805@tabi.org> In-Reply-To: <526FAD41.2000805@tabi.org> Content-Type: text/plain; charset="iso-8859-1" MIME-Version: 1.0 Cc: "mark.rutland@arm.com" , "devicetree@vger.kernel.org" , "alsa-devel@alsa-project.org" , "pawel.moll@arm.com" , "linux-doc@vger.kernel.org" , "s.hauer@pengutronix.de" , "swarren@wwwdotorg.org" , "linux-kernel@vger.kernel.org" , "rob.herring@calxeda.com" , Huang Shijie-B32955 , "broonie@kernel.org" , "ijc+devicetree@hellion.org.uk" , "dmaengine@vger.kernel.org" , "shawn.guo@linaro.org" , "linuxppc-dev@lists.ozlabs.org" , "linux-arm-kernel@lists.infradead.org" List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Without dual fifo support, handware underrun would occasionally occur and = then two audio channels would physically swap. This could be easily reprodu= ced in low bus frequency situation, while it would be better if we enable d= ual fifo. Sent by Android device. Timur Tabi wrote: Nicolin Chen wrote: > By enabling dual fifo mode, it would allow SSI enter a better performance > to transimit/receive data without occasional hardware underrun/overrun. Have you measured any real performance gain with this patch? I considered adding dual-FIFO support when I originally wrote this driver, but it didn't appear to have any real benefit, but it used twice as many DMA channels. I'm concerned that this is another patch that just enables a useless feature.